Bauhaus-Universität Weimar

between the individual particles of the water, and of that between 
the individual particles of the salt. This compound attraction is sup¬ 
posed to be more powerful than the simple attraction between the 
particles of water.* § The second explanation is the following:—The 
animal bladder, inasmuch as it is porous, may be viewed as a sys¬ 
tem of capillary tubes exerting attraction on the fluids, which are 
tending through their medium to mix with each other. If, now, one 
of the fluids be more strongly attracted by the tissue of the bladder 
than the other, it will, of course, be longer retained in its passage 
through the pores; and while the level of the fluid which passes 
through more quickly will necessarily fall in the vessel that contains 
it, that of the slowly traversing one will rise until the increasing 
pressure of the rising column of water counterbalances the effect of 
the more powerful attraction.! 
Dutrochet has named the phenomena which we have described 
“endosmose” and “exosmose,” according as the quantity of the one 
or of the other fluid increases under different conditions. In the 
direct passage of matters in solution into the capillaries and the 
blood, endosmose without doubt takes place, and not merely simple 
imbibition. Dutrochet has demonstrated this by experiment. A por¬ 
tion of the intestine of a young fowl, half filled with a solution of 
gum, sugar, or common salt, and tied at both ends, was placed in a 
shallow vessel filled with water, when it soon became filled to dis¬ 
tension. If, on the contrary, the intestine contained pure water, 
and was immersed in sugared water, it became gradually more lax, 
and the fluid in the intestine was afterwards found to contain sugar.J 
Dutrochet’s hypothesis, that electric action is connected with 
these phenomena, has not been confirmed: nor does it constantly 
happen that the denser fluid attracts more of the thinner than the 
latter does of the former: in the case of gases especially, the contrary 
is sometimes seen to be the case. But the chemical constitution of 
the fluid, and its physical and chemical relation to the animal mem¬ 
brane which it permeates, seem to have an important influence on 
the phenomenon. Dilute alcohol kept in a bladder becomes more 
concentrated, the water alone evaporating;§ and it has been found 
that if a portion of the intestine of a fowl filled with a watery solution 
of acacia gum and rhabarbarin, and tied close, is laid in a vessel con¬ 
taining water, the intestine becomes distended, while the rhabarbarin 
exudes from it. Similar sacks filled with a weak solution of sulphate 
of iron, and laid in a solution of ferrocyanate of potash, became dis¬ 
tended in consequence of the endosmosis of the water of the external 
solution, which at the same time acquired a blue colour from the 
* Berzelius, loc. cit. p. 134. 
f Biot, Experimental-Physik, translated into the German by Fechner, i. 384. 
See also Poisson, in PoggendorFs Annal, xi. 134. Fischer, ibid. 126. Magnus, 
ibid. x. 153; and Wach, Schweigg. Journal, p. 20. 
J Dutrochet, L’Agent immédiat du mouvement vital. Paris, 1826. Nouv. Rech. 
sur l’endosmose. Paris, 1828. #See also the article Endosmose in the Cyclopaedia 
of Anatomy. 
§ See experiments of Staples in Kastner’s Arch* für Chemie, Bd. iii. H. 1—3, 
p. 282.


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